When an infection occurs, our immune system triggers an “aggressive reaction”: A large number of so-called “killer immune cells” called CD8+ T cells are produced. These recognize and destroy all those cells infected with the invading pathogen. The number of “killer cells” produced depends on the extent of the infection. Once the infection has been brought under control, most CD8+ T cells die again. However, a small number of these CD8+T cells survive. These so-called memory cells “remember” the former pathogen so that they can help the immune system to react faster and more effectively when the pathogen enters the body again.
These memory cells are also crucial for the effectiveness of vaccines. During vaccination, dead or weakened pathogens are introduced into the body. Although this does not cause infection, it allows the immune system to form memory cells able to fend off the same pathogen in the future. However, vaccines only work for people who are able to produce and maintain memory cells, which is no longer the case for many older people.
In one of the most renowned scientific newspapers (eLife), a revolutionary study from Oxford has now been published. The study, led by Prof. Puleston, shows how autophagy, activated by spermidine, can restore this ability to form and maintain memory cells, which is often lost in old age.
Autophagy destroys and removes the “cell waste” and toxins that all cells accumulate over time as a result of normal cell function. The study shows that autophagy usually begins to fail in older mice. As a result, the “unpurified cells” are no longer able to form the necessary memory cells. This is also confirmed by the fact that mice which lack an important gene for autophagy do not produce memory cells after infection with viruses (such as influenza).
Prof. Puleston now shows that autophagy, which was activated with the help of the polyamine spermidine, restores the ability of older mice to form and maintain memory cells. Spermidine-treated mice developed stronger immunity to influenza after vaccination than other mice of similar age that were not treated with spermidine.
First research results also show an identical picture in human immune cells. The research team says that further scientific work is needed to better understand the positive effects of autophagy and spermidine on our immune system. Nevertheless, the results to date already speak of sensational research results.